Making textile strands

ABSTRACT

There is disclosed a method for making a textile strand comprising passing two filamentous strands together through a jet device which commingles filaments of the two strands and then subjecting the thus commingled strands to a drawing step in which at least one of the strands is drawn to a stable drawn state.

This invention relates to making textile strands.

FIELD OF THE INVENTION

EP-A-0 037 118 describes methods for making a bulky flat yarn comprisingpreparing at least two kinds of thermoplastic synthetic undrawn yarnshaving different natural draw ratios, simultaneously drawing theseprepared yarns at a draw ratio which is equal to or larger than thesmallest natural draw ratio of the yarns and releasing drawing tensionin the yarns after they are drawn. The yarns are mixed by means of aninterlacing nozzle before or after they are drawn. These operations,utilising differences in the elastic recovery of the constituent yarnsrather than their shrinkage properties, produce a filament yarn havinghigh bulk and resiliency, without any crimps.

In the article "Lufttexturierung: Produkte und Technologie" (Airtexturing: Products and Technology), E. Kreuzer;Chemiefasern/Textilindustrie 35, 87 Jahrgang, October 1985, pages 674 to678, the texturizing machine FK6T-80 is described, and the possibilitiesfor arranging the machine components to perform different texturingoperations explained.

EP-0 057 583 discloses a method for making a textile strand involvingdifferentially overfeeding two separate filamentous strands to a jetdevice which commingles and interlaces and forms loops in the filamentsof the strands and then subjecting the commingled strand to a heatingstep in which loops formed by the jet are pulled out and in so doingtighten any entanglements present as a result of the jet treatment andthus consolidate the strand. A "twistless" sewing thread can be producedin this way, "twistless" implying not that the thread is without twist,because twist can always be added, but rather that the thread has beenproduced without the need for twisting which is implicit in theproduction of sewing thread from staple fibre such as cotton.

The method of EP-0 057 583 is capable of modification to vary theproperties of the strand produced and, especially when sewing thread isbeing produced, can be adapted to produce a more or less "loopy" thread.It is sometimes suggested that the presence of loops in the thread canassist cooling of a sewing machine needle.

All modifications which have been suggested to the fundamental methodsof EP-0 057 583 have, however, not resulted in a more economicalproduction of a sewing thread, nor, indeed, could any more economicalproduction be envisioned, since the method itself eliminates the majorcost component of the production of conventional sewing thread, namelythe twisting step or steps involved in consolidating the staple fibresinto a coherent yarn.

The present invention provides methods for making a textile strandwhich, while maintaining the flexibility of the method of EP-0 057 583for the production of different specifications of strand, especially inthe context of sewing thread, gives, at the same time, the possibilityof substantial cost reductions in the process.

SUMMARY OF THE INVENTION

The invention comprises a method for making a textile strand comprisingpassing two filamentous strands together through a jet device whichcommingles filaments of the two strands and then subjecting the thuscommingled strands to a drawing step in which at least one of thestrands is drawn to a stable drawn state.

The strands may be dissimilar.

The strands may be dissimilar in the extent to which they can be drawn.They may be partially drawn before the jet, and they may have beendifferentially overfed to the jet.

One strand may be overfed to the jet. Typical overfeeds may be 40% to60%, but smaller and larger overfeeds may be useful in differentcircumstances.

The strands may be of the same polymer material, and will usually bemultifilament strands, but three or more strands may be used, and onesuch may be a monofilament or a low filament count strand. Staple fibrestrand may also be incorporated.

The commingled, drawn strand may be subjected to a heating step--theheating step may be at a temperature at which shrinkage (or moreshrinkage would take place were the strand not held to length orpermitted to contract by only a limited amount. A higher temperature maybe employed to yield higher tenacity in the finished thread.

The invention also comprises a textile strand made by a process asdisclosed, and such strand may comprise a sewing thread.

BRIEF DESCRIPTION OF THE DRAWINGS

Methods for making textile strands according to the invention will nowbe described with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of one method;

FIG. 2 is a diagrammatic illustration of another method; and

FIG. 3 is a diagrammatic illustration of yet another method.

DETAILED DESCRIPTION OF THE INVENTION

The methods illustrated in FIGS. 1 and 2 comprise passing two dissimilarfilamentous strands 11,12 together through a jet device 13 whichcommingles and forms loops in the filaments of the two strands 11,12 andthen subjecting the thus commingled strands to a drawing step 14 inwhich at least one of the strands is drawn to a stable drawn state.

By "stable drawn state" is meant a state in which, at the temperature atwhich a finished product will be used--in the case of ordinary textilestrands, such for example as those used as sewing threads, this will ofcourse be room temperature and probably extend up to normal laundering,cleaning and pressing temperatures--the strand will extend under tensionelastically, at least initially, rather than inelastically (with plasticor drawing extension).

If the strands are of different weights, one, perhaps, constituting acore or load-bearing strand, the other being an effect or bindingstrand--it will usually be preferred that the heavier or core strand isdrawn to the stable drawn state.

The strands 11,12 may be dissimilar in the extent to which they can bedrawn.

FIG. 1 illustrates a method in which strands 11,12 start out (or atleast may start out) as similar strands supplied on packages 111,121,both, perhaps, being of POY. The two strands as supplied from packages111,121 are drawn by differential speed godets 112,113; 122,123. Thedraw ratios achieved by godet pairs 112, 113;122,123 may each besubstantially less than the full extent to which it is possible to drawthe strands. Strand 11 may be drawn with a ratio 1.84:1, strand 12 witha ratio 1.78:1. Godet 123 may be arranged to rotate faster, by, say, 40%or 60% or even more, than godet 113 so as to overfeed strand 12 to thejet 13, by more than strand 11 is overfed thereto. The commingled strandis further drawn in the drawing stage 14 at a ratio 1.27:1.

The drawing stage 14 comprises input godet 141, and output hot godet142. The drawn strand from godet 142 is then overfed 21/2%-4% to afurther godet 15. The thus hot relaxed strand is wound up.

In the method of EP-0 057 583 the speed at which the strand is wound updepends upon the rate at which the jet can handle the strands. In thepresent method, the strands are subject to a further drawing stage afterthe jet. In the method of FIG. 1 this drawing stage is carried out at adraw ratio of 1.27:1. The finished strand is thus wound up some 27%faster than is possible in the method as described in EP-0 057 583.

FIG. 2 illustrates a method in which dissimilar starting materials areused as strands 11,12, supplied from packages 211,221 and fed togetherto a drawing stage between godets 202,203. The strands 11,12 aredissimilar at least in regard to the extent to which they can be drawn.The partially drawn strand combination 11,12 is overfed to the jet 13where the filaments of the strands 11,12 are commingled.

The commingled strand is drawn in the drawing stage 14 and when itleaves that stage the filaments contributed by strands 11,12 will havedifferential shrinkage because one of the strands will have been drawnto a lesser proportion of its possible draw ratio than the other. Thedrawn strand from the drawing stage 14 comprising input and outputgodets 141,143 is subjected to a heating step by plate heater 215 whilebeing held to length or allowed to have controlled shrinkage (or even,perhaps, stretched a little more) by a further godet roll 216 from whereit is forwarded to a wind-up package 17.

FIG. 3 illustrates a method generally like that illustrated in FIG. 1but in which no drawing takes place before the jet. Strands 11 and 12both of POY but with strand 11 used as an effect yarn of lower dtex thanstrand 12 are overfed to a drawing stage 14 by feed rollers 113,123.Feed roller 113, as before, overfeeds by 40% (or more or less) withrespect to the first-encountered roller 141 of the drawing stage 14,while feed roller 123 overfeeds by, say, 4.5% relative to that sameroller 141. The commingled strands from the jet 13 are then drawn to thenormal extent to which such yarns are hot drawn, or even overdrawn, inthe drawing stage 14 and subsequently subjected to hot relaxationbetween the hot godet 142 and a godet 15 as before.

It will be noted that in the method of FIG. 1, the wind-up arrangement18 is overend, as by a ring and traveller, while in FIGS. 2 and 3 a sidewind-up 17 is illustrated. The thread wound up in the method of FIG. 1will have some twist inserted during winding. Twist may be desirable forcertain end uses, although for sewing thread, for example, the amount oftwist which may be inserted to improve the sewing properties over thethread as produced without twist will be very substantially less thanthe twist required to make thread from staple fibres. The cost ofmanufacture of sewing thread can then be very much reduced by processesaccording to the present invention where twist is not required, or isnot required to anything like the same extent.

When a side wind-up is used, any desired amount of twist may be insertedin a subsequent operation.

Consolidation of the thread is effected, or at least assisted, by thecommingling effect of the jet 13 and the subsequent tightening broughtabout by the processes after the jet.

The methods described are particularly advantageous over other methodsof producing coherent twist-free or low-twist strands in which drawingis effected completely before a jet commingling device inasmuch as thethroughput of such methods is limited by the jet. With the presentmethods, a substantial proportion or indeed all of the draw is effectedafter the jet and this in effect means that the strand is producedcorrespondingly faster.

On the other hand, even delaying a small proportion of the draw untilafter commingling in the jet can have beneficial effects, producing afiner strand which has a higher tenacity (by as much as 10%) than if allthe drawing is effected before the jet. At the same time any tendency toindividual filament breakage on drawing before the jet is reduced andthe resulting strand is noticeably smoother.

Many variations can be played on the basic method as defined above anddescribed with reference to the drawings. For example, hot drawpin or aplate heater may be used for hot drawing instead of the hot roller asdescribed; cold drawing may be appropriate in some circumstances.

And the possibility of filament breakage may itself be turned to goodeffect by inducing filament breakage after the jet to produce a threadwith controlled filament breakage which would more resemble a spunthread.

We claim:
 1. A method for making a coherent twist-free or low-twisttextile strand, the method comprising the steps of:passing a pluralityof incompletely drawn filamentous strands together through a jet deviceto commingle filaments of the strands and forms loops therein, thestrands being drawable; then drawing at least one of the filamentousstrands to a stable drawn state, wherein the loops formed by the jet arepulled out and the textile strand is consolidated.
 2. The methodaccording to claim 1, in which the filamentous strands are dissimilar inthe extent to which they can be drawn.
 3. The method according to claim1, in which the filamentous strands are partially drawn before passingthrough the jet device.
 4. The method according to claim 1, in which thefilamentous strands are differentially overfed to the jet device.
 5. Themethod according to claim 1, in which one filamentous strand is overfedby up to 40% to the jet.
 6. The method according to claim 1, in whichthe strands are of the same polymer material.
 7. The method according toclaim 1, in which the strands are both multifilament strands.
 8. Amethod according to claim 1, in which the commingled, drawn strand issubjected to a heating step.
 9. A process for making a coherenttwist-free or low-twist textile strand, the comprising the stepsof:passing at least two separate filamentous strands together through ajet device which commingles filaments of the strands and thereby forms acommingled strand; overfeeding at least one of the strands into the jetdevice wherein the jet device forms loops in the filaments of at leastone strand and entanglements to form a bulky commingled strand; drawingthe bulky commingled strands, strands being heated during the drawingstep, wherein the bulky commingled strand is consolidated by tighteningand pulling out the loops and entanglements formed by the jet device.10. The process according to claim 9, in which the filamentous strandsare dissimilar in the extent to which they can be drawn.
 11. The processaccording to claim 9, in which the filamentous strands are partiallydrawn before passing through the jet device.
 12. The process accordingto claim 9, in which the filamentous strands are differentially overfedto the jet device.
 13. The process according to claims 9, in which onefilamentous strand is overfed by up to 40% to the jet.
 14. The processaccording to claim 9, in which the strands are of the same polymermaterial.
 15. The process according to claim 9, in which the strands areboth multifilament strands.
 16. A method according to claim 9, in whichthe commingled, drawn strand is subjected to a heating step.
 17. Aprocess for making a coherent twist-free or low-twist textile strand,the comprising the steps of:passing at least two separate filamentousstrands together through a jet device which commingles filaments of thestrands and thereby forms a commingled strand; the strands being overfedinto the jet device whereby the jet device forms loops in the filamentsof at least one strand and entanglements to form a bulky commingledstrand; the separate strands being drawable and at least one of thembeing overdrawn during the process; at least the overdrawn strand beingheat treated during the process; the bulky commingled strand beingdrawable after leaving the jet device and being treated after the jetdevice to complete the drawing process wherein the strand isconsolidated by tightening brought about thereby and loops formed by thejet device are pulled out and entanglements formed by the jet device aretightened.
 18. The process according to claim 17, in which thefilamentous strands are dissimilar in the extent to which they can bedrawn.
 19. The process according to claim 17, in which the filamentousstrands are partially drawn before passing through the jet device. 20.The process according to claim 17, in which the filamentous strands aredifferentially overfed to the jet device.
 21. The process according toclaims 17, in which one filamentous strand is overfed by up to 40% tothe jet.
 22. The process according to claim 17, in which the strands areof the same polymer material.
 23. The process according to claim 17, inwhich the strands are both multifilament strands.
 24. A method accordingto claim 17, in which the commingled, drawn strand is subjected to aheating step.